U.S. patent number 7,262,947 [Application Number 10/799,141] was granted by the patent office on 2007-08-28 for low voltage interrupter for electric winch.
This patent grant is currently assigned to Warn Industries, Inc.. Invention is credited to Oliver Heravi, Mitchell R Lawson.
United States Patent |
7,262,947 |
Heravi , et al. |
August 28, 2007 |
**Please see images for:
( Certificate of Correction ) ** |
Low voltage interrupter for electric winch
Abstract
A low voltage interrupt for an electric winch prevents voltage
decay of a battery due to excessive operation of the winch. If the
battery voltage decays below a threshold, the low voltage interrupt
disables the winch, allowing an alternator to recharge the battery.
A voltage sense circuit determines the voltage of the battery. The
sensed voltage is compared to a predetermined threshold. If the
sensed voltage decays below the threshold, the low voltage
interrupt generates an interrupt signal. The interrupt signal
causes a relay to actuate, thereby interrupting current to the
winch.
Inventors: |
Heravi; Oliver (Tigard, OR),
Lawson; Mitchell R (Vancouver, WA) |
Assignee: |
Warn Industries, Inc.
(Milwaukie, OR)
|
Family
ID: |
34988710 |
Appl.
No.: |
10/799,141 |
Filed: |
March 12, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20050211966 A1 |
Sep 29, 2005 |
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Current U.S.
Class: |
361/92 |
Current CPC
Class: |
B66D
1/40 (20130101); H02J 7/0063 (20130101); H02J
7/007182 (20200101); H02J 7/0031 (20130101); H02J
7/00306 (20200101); H02J 2007/0067 (20130101) |
Current International
Class: |
H02H
3/00 (20060101) |
Field of
Search: |
;361/92 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Jackson; Stephen W.
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Claims
What is claimed is:
1. A low voltage interrupt system for an electric winch comprising:
a vehicle electrical supply that provides current to the electric
winch; a voltage sense circuit that determines a voltage of the
vehicle electrical supply; a controller that compares the voltage
to a threshold voltage at a first instance and generates an
interrupt signal if the voltage is below the threshold voltage for
a first period; and a relay that actuates in response to the
interrupt signal, thereby interrupting the current to the electric
winch, wherein the first period is greater than or equal to a timed
low voltage period.
2. The system of claim 1 wherein the vehicle electrical supply
includes a battery.
3. The system of claim 1 wherein the voltage sense circuit includes
an A/D converter that samples the voltage of the vehicle electrical
supply.
4. A low voltage interrupt system for an electric winch comprising:
a vehicle electrical supply that provides current to the electric
winch; a voltage sense circuit that determines a voltage of the
vehicle electrical supply; a controller that compares the voltage
to a threshold voltage at a first instance and generates an
interrupt signal if the voltage is below the threshold voltage for
a first period; and a relay that actuates in response to the
interrupt signal, thereby interrupting the current to the electric
winch, wherein the relay interrupts the current for a second period
and the second period is greater than or equal to a timer
period.
5. The system of claim 4 wherein the controller compares the
voltage to the threshold voltage at a second instance after the
second period.
6. The system of claim 5 wherein the controller terminates the
interrupt signal if the voltage is not below the threshold voltage
after the second period.
7. The system of claim 1 further comprising an alternator that
recharges the vehicle electrical supply.
8. The system of claim 4 wherein the controller compares the
voltage to an enable voltage at a second instance after the second
period, wherein the enable voltage is greater than the threshold
voltage.
9. The system of claim 8 wherein the controller terminates the
interrupt signal if the voltage is not below the enable voltage
after the second period.
10. A low voltage interrupt method for an electric winch
comprising: providing a current from a vehicle electrical supply to
the electric winch; determining a voltage of the vehicle electrical
supply; comparing the voltage to a low voltage threshold at a first
instance; generating an interrupt signal if the voltage is less
than the low voltage threshold for a first period; and receiving
the interrupt signal at a relay that interrupts the current in
response to the interrupt signal, wherein the first period is
greater than or equal to a timed low voltage period.
11. The method of claim 10 wherein the step of determining the
voltage includes sampling the voltage at an A/D converter.
12. A low voltage interrupt method for an electric winch
comprising: providing a current from a vehicle electrical supply to
the electric winch; determining a voltage of the vehicle electrical
supply; comparing the voltage to a low voltage threshold at a first
instance; generating an interrupt signal if the voltage is less
than the low voltage threshold for a first period; and receiving
the interrupt signal at a relay that interrupts the current in
response to the interrupt signal, wherein the step of interrupting
the current includes interrupting the current for a second period
that is greater than or equal to a timer period.
13. The method of claim 12 further comprising comparing the voltage
to the low voltage threshold at a second instance after the second
period.
14. The method of claim 13 further comprising terminating the
interrupt signal if the voltage is not below the low voltage
threshold after the second period.
15. The method of claim 12 further comprising comparing the voltage
to an enable voltage threshold at a second instance after the
second period, wherein the enable voltage is greater than the low
voltage threshold.
16. The method of claim 15 further comprising terminating the
interrupt signal if the voltage is not below the enable voltage
threshold after the second period.
Description
FIELD OF THE INVENTION
The present invention relates to an electric winch, and more
particularly to compensating for a low voltage condition in a
battery and/or charging system of an electric winch.
BACKGROUND OF THE INVENTION
Winches used to pull or lift heavy loads support a wide range of
applications and assume a variety of sizes and types.
Electrically-powered winches require a voltage supply to power the
winch motor. A vehicle may incorporate a winch and power the winch
with the vehicle battery and/or electrical system.
Frequent and excessive operation of the winch may result in an
undue demand of current from the electrical supply. The current
used by the winch may exceed the current supplied to the battery by
a vehicle alternator. Continuous operation of the winch under this
condition may cause the battery voltage to decay. Low battery
voltage may cause performance issues with the winch or other
electromechanical devices in the system. For example, low battery
voltage reduces the speed of the winch motor, causing the motor to
run for a longer period of time in order to pull a given load.
Consequently, more heat is generated in the motor. Additionally,
the battery may not be able to provide sufficient voltage to start
the vehicle.
SUMMARY OF THE INVENTION
A low voltage interrupt system for an electric winch comprises an
electrical supply that provides current to the electric winch. A
voltage sense circuit determines a voltage of the electrical
supply. A controller compares the voltage to a threshold voltage
and generates an interrupt signal if the voltage is below the
threshold voltage for a first period. A relay actuates in response
to the interrupt signal, thereby interrupting the current to the
electric winch.
In another aspect of the invention, a low voltage interrupt method
for an electric winch comprises providing a current from an
electrical supply to the electric winch. A voltage of the
electrical supply is determined. The voltage is compared to a low
voltage threshold. An interrupt signal is generated if the voltage
is less than the low voltage threshold for a first period. The
interrupt signal is received at a relay. The relay interrupts the
current in response to the interrupt signal.
Further areas of applicability of the present invention will become
apparent from the detailed description provided hereinafter. It
should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the
detailed description and the accompanying drawings, wherein:
FIG. 1 is a functional block diagram of a low voltage interrupter
circuit according to the present invention;
FIG. 2 is a circuit diagram of a low voltage interrupter circuit
according to the present invention;
FIG. 3 graphically illustrates a battery voltage signal and a low
voltage interrupt signal according to the present invention;
and
FIG. 4 is a flow diagram of a low voltage interrupter algorithm
according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiment(s) is merely
exemplary in nature and is in no way intended to limit the
invention, its application, or uses. For purposes of clarity, the
same reference numbers will be used in the drawings to identify
similar elements.
A low voltage interrupter system 10 for an electric winch includes
a voltage sense circuit 12 and a switch 14 as shown in FIG. 1. The
voltage sense circuit 12 senses a voltage from a battery 16. The
battery 16 supplies electrical power to various electro-mechanical
devices in a vehicle having a winch system. For example, the
battery 16 provides electrical power to vehicle accessories such as
head lights, tail lights, the HVAC blower motor, and radio, as well
as the voltage sense circuit 12, a winch driving circuit 18
including a solenoid pack, and an electric winch 20. As is known in
the art, the battery 16 may provide electrical power to additional
devices of the winch system.
The battery 16 is charged by an alternator 22 of a vehicle (not
shown). However, operation of the winch 20 may drain the voltage of
the battery 16 at a rate faster than the alternator 22 can charge
the battery 16. For example, the battery 16 may provide a system
voltage of approximately 12 v. Operation of the winch 20 may cause
the battery 16 to provide a voltage less than 12 v. As a result,
certain electrical or electro-mechanical functions in the system
may not perform as desired. The performance or reliability of the
battery 16 may be reduced due to a lower operating voltage.
Similarly, the operating speed of the winch 20 may be reduced.
The voltage sense circuit 12 senses the voltage of the battery 16
to determine if the voltage is below a threshold voltage. The
voltage sense circuit 12 is operable to sense the effective voltage
of the battery 16 at any location in the winch system. If the
voltage sense circuit 12 determines that the voltage of the battery
16 is below the threshold voltage, the voltage sense circuit 12
generates a low voltage interrupt signal 24. The switch 14 actuates
to an open position in response to the low voltage interrupt signal
24. If the switch 14 is in an open position, the solenoid pack 18
does not receive electrical power from the battery 16. Therefore,
operation of the winch 20 is interrupted. While the operation of
the winch 20 is interrupted, the alternator 22 is able to charge
the battery 16 more effectively.
Referring now to FIG. 2, the low voltage sense circuit 12 comprises
a microcontroller unit 30. The microcontroller unit 30 includes an
analog-to-digital (A/D) converter that samples the voltage from the
battery 16. The microcontroller unit 30 differentiates the actual
voltage of the battery 16 from other voltages of the electrical
system. Other factors affecting the voltage signal include a
transient voltage caused by winch inrush current or ripple voltage
caused by alternator rotation. Microcontroller, sampling, and other
computational functions may be performed on an integrated circuit,
as shown, or each may be performed by a dedicated circuit as is
known in the art.
The winch driving circuit 18 selectively provides electrical energy
to rotate a winch armature 32 in a first direction or a second
direction as is known in the art. Additionally, the winch driving
circuit 18 is operable to provide no electrical energy to the
armature 32, thereby halting the operation of the winch. The winch
driving circuit 18, for example, includes four solenoids 34, 36,
38, 40 in an H-bridge configuration. A voltage signal applied at
solenoid pack terminals 56, 58 affects the operation of the
solenoids 34, 36, 38, 40. For example, a voltage applied at a first
terminal 56 energizes solenoids 36 and 38. Energizing solenoids 36
and 38 causes current to flow from an input terminal 42 in a
direction 44. Current flow in direction 44 through a field 46
causes the armature 32 to rotate in a first direction 48.
Conversely, a voltage applied at a second terminal 58 energizes
solenoids 34 and 40. Energizing solenoids 34 and 40 causes current
to flow from the input terminal 42 in a direction 50. Current flow
in direction 50 through the field 46 causes the armature 32 to
rotate in a second direction 52.
The switch 14 comprises, for example, a relay 54. The relay 54
provides a connection between the solenoid pack terminals 42, 44
and a ground 59, allowing current to flow selectively through the
solenoids 34, 36, 38, 40. The relay 54 receives the low voltage
interrupt signal 24 from the microcontroller unit 30. The low
voltage interrupt signal 24 defaults to a first state wherein the
relay 54 is closed. For example, the low voltage interrupt signal
24 may default to 0 v. If the voltage from the battery 16 drops
below the threshold voltage, the microcontroller unit 30 causes the
low voltage interrupt signal 24 to a second state. As a result, the
relay 54 opens. With the relay 54 in an open position, all of the
solenoids 34, 36, 38, 40 are de-energized. Therefore, the armature
32 does not receive electrical energy from the winch driving
circuit 18, causing operation of the winch to halt.
The low voltage interrupt signal 24 is generated in response to the
voltage signal 60 from the battery as shown in FIG. 3. At time t1,
the voltage signal 60 is approximately equal to or slightly above
the threshold voltage 62. For example, a nominal voltage of the
voltage signal 60 may be 12 v, and the threshold voltage 62 may be
10 v. The low voltage interrupt signal 24 is a first state at time
t1. While the voltage signal 60 provided by the battery is a DC
voltage, the operation of the alternator may cause a ripple voltage
64 in the voltage signal 60. In certain circumstances, the ripple
voltage 64 may cause the voltage signal 60 to drop below the
threshold voltage 62. The voltage signal 60 may be rectified or
filtered to minimize the effect of the ripple voltage 64.
An inrush current causes a transient voltage 66 at time t2. The
inrush current is a result of the beginning of the operation of the
winch. The alternator is not able to charge the battery enough to
compensate for the voltage required by the winch. Therefore, the
voltage signal 60 begins to decay. At time t3, the microcontroller
senses that the voltage signal 60 has decayed below the threshold
voltage 62. The microcontroller causes the voltage interrupt signal
24 to change from the first state to a second state. For example,
the voltage interrupt signal 24 may change from 0 v to 5 v. When
the voltage interrupt signal 24 is the second state, the relay of
FIG. 2 is energized, interrupting the current through the
solenoids. The relay is energized for a predetermined period 68 to
allow the alternator to charge the battery. For example, the
predetermined period 68 may be 30 seconds. After the predetermined
period 68 is elapsed, the microcontroller determines if the voltage
signal 60 is still below the threshold voltage 62. If the voltage
signal 60 is below the threshold voltage 62 after the predetermined
period 68, the microcontroller continues to energize the relay.
Alternatively, the relay may be energized until the microcontroller
senses that the voltage signal 60 is charged above the threshold
voltage 62.
A low voltage interrupter algorithm 80 is shown in FIG. 4. The
algorithm 80 starts at the power-up of the vehicle or winch system.
A startup timer is initialized at step 82. The startup timer
ensures that the algorithm 80 does not initiate a low voltage
interrupt prematurely. The electrical system of the vehicle may be
unstable immediately after power-up, resulting in an unstable
voltage signal. At step 84, the algorithm 80 determines if a proper
startup period has elapsed. In an exemplary embodiment, the startup
period is 50 ms. If the startup timer has not reached 50 ms, step
84 is repeated. After the startup timer reaches the proper period,
the algorithm 80 continues to step 86.
At step 86, the algorithm 80 determines if the voltage signal from
the battery is below the low voltage threshold. If the voltage
signal is not below the low voltage threshold, the algorithm
continues to step 88. If the voltage signal is below the low
voltage threshold, the algorithm 80 determines if the voltage
signal bas been below the low voltage threshold for a low voltage
period at step 90. In an exemplary embodiment, the low voltage
period is 600 ms. During operation of the winch, system noise or
voltage transients may cause the voltage signal to fall below the
low voltage threshold temporarily. The low voltage period ensures
that the algorithm 80 does not initiate a low voltage interrupt due
to a temporary voltage drop. If the voltage signal is not below the
low voltage threshold for 600 ms, the algorithm 80 continues to
check the voltage signal at step 86. If the voltage signal is below
the low voltage threshold continuously for 600 ms, the algorithm 80
disables the winch motor at step 92.
A flag is set at step 94 to indicate that the algorithm 80
initiated a low voltage interrupt. An interrupt timer is checked at
step 96 to determine if the low voltage interrupt has been active
for a disable period. The interrupt timer ensures that the winch
motor is disabled for the disable period before allowing the
algorithm 80 to re-enable the winch motor. In the preferred
embodiment, the disable period is 30 seconds. If the disable period
has not elapsed, the algorithm 80 checks the voltage signal again
at step 86. If the voltage signal is still below the low voltage
threshold, the algorithm 80 continues through to step 96 to recheck
the disable period. If the voltage signal is not below the low
voltage threshold, the algorithm 80 determines if the flag was
previously set at step 88. If the flag was set, the algorithm 80
continues to step 96. If the flag was not set, the algorithm 80
returns to step 86.
If the disable period is elapsed at step 96, the algorithm 80
rechecks the voltage signal at step 98. If the voltage signal is
still below the low voltage threshold, the algorithm 80 returns to
step 92. If the voltage signal is above the low voltage threshold,
the algorithm 80 enables the winch motor and clears the flag at
step 100. The algorithm then continues to check for a low voltage
signal at step 84. In alternative embodiments, the algorithm 80 may
require that the voltage signal increase to a second threshold. For
example, the algorithm 80 may continue with the winch motor
disabled until the voltage signal attains a specific voltage level
above the low voltage threshold.
The description of the invention is merely exemplary in nature and,
thus, variations that do not depart from the gist of the invention
are intended to be within the scope of the invention. Such
variations are not to be regarded as a departure from the spirit
and scope of the invention.
* * * * *